The present invention relates to vehicle monitoring systems. More particularly, the invention relates to an addressable monitoring system for a vehicle.
Old systems and methods used to check or monitor vehicle parameters, such as tire pressure, generally require manual inspections at regular intervals with mechanical gauges. Manual inspections are usually inconvenient and possibly unreliable tasks. In addition, such inspections do not provide information on demand while a vehicle is moving. For these reasons, automated monitoring systems have been developed.
Automated vehicle monitoring systems can enhance the performance and safety of a motor vehicle. For example, a tire pressure monitoring system can be used to alert an operator of an incorrectly inflated tire. An incorrectly inflated tire can undergo uneven wear, lower vehicle fuel efficiency, and compromise safe handling of the vehicle.
One known vehicle monitoring system includes an air pressure sensor and transmitter/receiver mounted on or inside each tire (the sensor and transmitter/receiver are sometimes collectively and generically referred to as a xe2x80x9csensorxe2x80x9d). The transmitter/receivers may be programmed or otherwise configured to periodically send information via radio waves (RF) to a central receiver. The central receiver may be coupled to a display or other device that provides human-readable output. When information is desired at a non-periodic interval or time, the transmitter/receivers may be activated (i.e., caused to read or obtain information from the sensor and then transmit that information to the central receiver) by using separate transmitters (often referred to as xe2x80x9cinitiatorsxe2x80x9d or xe2x80x9csensor initiatorsxe2x80x9d) that are mounted in close proximity to each transmitter/receiver. The initiator generates a low frequency modulated magnetic field of sufficient intensity to wake up the tire sensor. Each initiator is separately wired to a control unit (which may or may not be the central receiver). The system may require each initiator to have a unique pre-programmed or otherwise pre-configured identity such that information may be obtained from a specific tire.
While functional, existing tire pressure monitoring systems are not completely satisfactory. One problem with existing systems is that since each initiator in a multiplexed system has a unique identity, initiators are not easily interchangeable. Thus, when an initiator fails, then a specific, identical initiator rather than a generic replacement initiator must be installed in its place or the system must have the capability to xe2x80x9clearnxe2x80x9d the identity of the new initiator.
Herein, the term xe2x80x9csensorxe2x80x9d is used broadly. An individual xe2x80x9csensorxe2x80x9d may include or otherwise be associated with an activator or initiator as well as a transmitter and/or a receiver. In some embodiments, the initiator rather than the sensor itself may have an address input and be connected to the harness.
Accordingly, in one embodiment, the invention provides an addressable monitoring system for a vehicle. The system may be used to monitor tire pressure but may also be used in other monitoring applications. The system includes a plurality of sensors each having at least one address input, a harness and a controller. The harness includes a single bus line coupled to each of the plurality of sensors. Each sensor is operable to determine its own address according to the connection made between the harness and the sensor. When data from a particular sensor is desired (which might be determined based on input from a person in the vehicle), a controller sends a signal having address information and control information through the harness to each of the plurality of sensors. The address information is associated or correlated to the sensor of interest. Although all the sensors may receive the signal from the controller, only the sensor having the address that corresponds to the address information in the signal responds to the control information in the signal.
In another embodiment, the invention provides a method of addressing sensors in a vehicle. The method includes locating the sensors on a vehicle, connecting each sensor to a harness having a bus line and address connectors, and connecting the harness to a controller. The controller sends command signals with an address or address information through the harness to each of the plurality of sensors. Each sensor determines its own address according to the connection of the harness to at least one address input of the sensor. Thus, each sensor recognizes the command signals addressed to itself and ignores signals addressed to or intended for other sensors.
In yet another embodiment, the invention provides an addressable vehicle tire pressure monitoring system. The system includes a controller, a wiring harness, initiators, transmitters, and measurement devices at each tire. The common wiring harness includes a communication bus and address connectors. The controller sends address signals and control data through the common wiring harness to initiators located at each tire. Each initiator has inputs for two address connectors, a power line, a ground line, and a communication bus line. Each initiator determines its own address based upon the address connectors of the harness, such that each initiator is capable of recognizing a command signal addressed to itself. Upon receiving a command signal, the initiator activates a transmitter to transmit an air pressure reading from the tire to a controller (which may or may not be the controller that generates command signals for the initiators). The controller receives the transmitted signal, translates the information, and matches the address to a tire location. Because identity and address information is determined based upon its wire harness connection, each initiator can be identical with no requirement of preprogramming an identity into the initiator.
As is apparent from the above, it is an aspect of the invention to provide a method and system of identifying and addressing sensors in a vehicular monitoring system. Other features and aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.